Responsiveness of Noninvasive Continuous Cardiac Output Monitoring During the Valsalva Maneuver

Haemodynamic effects of a 10-min treatment with a high inspired oxygen concentration in the emergency department: a prospective observational study

Previous studies show that prolonged exposure to a high inspired oxygen concentration (FiO₂) is associated with unfavourable haemodynamic effects. Until now, it is unknown if similar effects also occur after oxygen therapy of limited duration in the emergency department (ED).

OBJECTIVES

To investigate the haemodynamic effects of a high FiO₂ administered for a limited duration of time in patients who receive preoxygenation for procedural sedation and analgesia (PSA) in the ED.

DESIGN, SETTINGS AND PARTICIPANTS

In a prospective cohort study, cardiac output (CO), stroke volume (SV) and systemic vascular resistance (SVR) were measured using the Clearsight non-invasive CO monitoring system in patients who received preoxygenation for PSA in the ED. Measurements were performed at baseline, after 5 min of preoxygenation via a non-rebreathing mask at 15 /L min and after 5 min of flush rate oxygen administration.

OUTCOMES MEASURES

The primary outcome was defined as the change in CO (L/min) from baseline after subsequent preoxygenation with 15 L/min and flush rate.

RESULTS

Sixty patients were included. Mean CO at baseline was 6.5 (6.0-6.9) L/min and decreased to 6.3 (5.8-6.8) L/min after 5 min of oxygen administration at a rate of 15 L/min, and to 6.2 (5.7-6.70) L/min after another 5 min at flush rate (p=0.037). Mean SV remained relatively constant during this period, whereas mean SVR increased markedly (from 781 (649-1067), to 1244 (936-1695) to 1337 (988-1738) dyn/s/cm^-5, p<0.001. Sixteen (27%) patients experienced a>10% decrease in CO.

CONCLUSION

Exposure of patients to a high FiO₂ for 5-10 min results in a significant drop in CO in one out of four patients. Therefore, even in the ED and in prehospital care, where oxygen is administered for a limited amount of time, FiO₂ should be titrated based on deficit whenever this is feasible and high flow oxygen should not be given as a routine treatment.

The safety of exercise for older patients with severe aortic stenosis undergoing conservative management: A narrative review

The incidence of aortic stenosis (AS) increases with age and is a serious problem in an aging society. In recent years, transcatheter aortic valve implantation (TAVI) has been performed widely; however, older patients may be ineligible for TAVI or surgical treatment because of medical ineligibility. Symptom-based rehabilitation is required for these patients to maintain and improve their physical function and ability to perform activities of daily living. No studies have examined exercise safety for older patients with severe AS who are ineligible for TAVI or surgery. We summarized the safety of exercise for older patients with severe AS, collecting 7 studies on maximal exercise stress tests and 16 studies on preoperative physical examinations. From this review, it may be unlikely that exercise under appropriate management can cause hemodynamic changes, leading to death. However, there were no studies on exercise intervention for older patients with AS who are chosen for conservative management. The optimal exercise intensity for symptomatic older patients with AS undergoing conservative management and the effects of continuous exercise intervention require future study.